A "fraud alert" is valid for only 90 days. A "security freeze" remains in place until you lift it with your PIN code, which is provided when you place the freeze.

FTC: https://www.consumer.ftc.gov/articles/0497-credit-freeze-faq...

Experian: https://www.experian.com/freeze/center.html

TransUnion: https://freeze.transunion.com/sf/securityFreeze/landingPage....